Production of tetrazoles



Patented Sept. 14, 1926.

UNITED STATES 1,599,493- PATENT OFFICE.

KARL FRIEDRICH SCHMIDT, OF HEIDELBERG, GERMANY,

assrenon TO xivom. a 00.,

OF LUDWIGSHAFEN-ON-THE-RHINE, GERMANY, AJTIRM COMPOSED OF ALBERT KNOLL,HANS KNOLL, AND MAX DAEG E.

PRODUCTION OF TETRAZQLES.

In my prior application for Letters Patent Serial No. 28,962, filed May8, 1925, which has matured into'U. S. Patent No. 1,564,631, grantedDecember 8, 1925, there is set forth a process for the production ofderivatives of hvpothetical imines including the amines and theirsubstitution products by treating hydrocarbons, ketones, alde-.

hydes and their derivatives with hydrazoic acid in the presence ofconcentrated mineral acids.

In this process the inter-reacting substances are united Thereby, theNH, resulting from the interaction of hydrazoic acid with the concen-'trated mineral acid, reacts with hydrocarbon derivatives, for example,ketones which are in normal manner transformed into for example,substituted acid amides.

The action of hydrazoic acid upon unsaturated compounds is indeedalready known (see, for example, Ohemisches Centralblatt, 1913, pages2024 and 1915, II, page 596). In these reactions however the hydrazoicacid is attached as a whole. There are thus formed by the addition ofN,H to unsaturated compounds, azides or their conversion products. Thesereactions are therefore characterized in that the resulting reactionproducts contain three more nitrogen atoms than the initial material.

The process set forth in my prior application provides a method for thedirect introduction of amido groups into hydrocarbons or theirderivatives. Prior to my invention set forth in the application referredto, the method employed usually comprised treating a nitro compound or aphenol compound whereby the characteristic groups of these compoundswere changed or modified. According to theinvention referred to, itbecame possible to introduce amido groups directly into numerous hdrocarbons and their derivatives by emp oying hydrazoic acid which iscaused to decompose under.

the influence of mineral acids. he hydrazoic acid is decomposed into Nand the residue NH, attaches itself for example, to benzol with theformation of aniline.

If the action of the decomposing hydrazoic acid occurs upon organiccompounds with double bonds (C=C, N=N, 0:0), for ex-- ample; aldehydes,keton s, unsaturated acids, ketone acids. the attaching of NH to the inmolecular quantities.

Drawing. Application filed December 11, 1925, Serial No. 74,884, and inGermany January 2, 1824. double bond occurs. With aldehydes, for.

example, nitrils .or the formyl compounds of the respective amines areformed.

It has been found that by the action of an excess of hydrazoic acid oncarbonyl compounds the reaction proceeds so that an-' 'om-om-on, m-on-on.

. NH+N1 Hz-CH; -0 Hg-CHr-C-O Cyclohexanone Leucin 1actam.' 2. Wlthexcess of N,,H:

on n H on n -on dn:11jb -dH Ztt-o N N+N +H 0 1 a u a a Pentamethylenetetrazol.

The addition of N H to nitrogen-free substances can, of course, resultonly in azides or their derivatives (see Gentralblatt 1915, II, 596)that is, substances containing three atoms of N. a

If, however, the reaction is explained as a subsequent llIllOIl of N Hwith leucin lactam, it then has no connection with the hitherto knowntetrazol synthesis, since it proceeds with splitting off of water. Noris any case known wherein use is made of hydrazoic acid on acid amidesor hypothetical intermediate products of the type Enramp le 1-,

while be- (2% mol.) fienzol, ether,

of hydrazoic acid issolved in tetraline, etc., after the addition of alittle acid. The yield of tetrazol compound is about 70%. Only e-leucinlactam is obtained as a by-product.

Example 2.

15.7 g. acetone are slowly dropped, with constant stirrin and icecooling, into a mixture of g. ,H, dissolved in about 500 com. of benzol,and ccm. concentrated H 5000 com. of N are thereby evolved. The acidstratum is then diluted with ice,

neutralized with sodium carbonate'and alcohol added tocompletely-precipitate out the sodium sulfate. A saturated sublimatesolution (that is acold saturated aqueous solution of mercuric chloride,about 4% HgOl is used to preci itate from the concentrated filtrate thedi cultly soluble HgCl molecule compound of the reaction product;melting pointlll".

The aqueous solution of this compound is then treated (decomposed) withhydrogen sulfide, the filtrate evaporated and the residuere-crystallized from ligroin. Melting point 71. Reaction neutral.'Analysis C l-LN The substance is N-C dimethyl tetrazol.

CHI-O as the cleavage (s litting up) into N, GO,

and 2 mol. methy amine shows. The yield is about 80% of the theoreticalyield.

E'wmple 3. Operation as above 6 g. N,H, 5.5 g. benzophenone. 1.68 g. 2were split oil. The

acld stratum, on termination of the ex eriment, solidified to acrystalline mash, w ich re-crystallized from benzol and alcohol, meltedat 163. Yield-6 g.

The reaction probably takes place in the following manner:

om-fi-cmq-amn-cmmn-p-n-ammm be used so lon as they do not ossess basicproperties which will destroy t e hydrazoic acid by neutralization.Besides inorganic catalysts, it has also been discovered that organiccatalysts, such as sul hoacetic acid SO,HGH COOH and et yl sulphuricacid ma be used. A gaseous substance as gaseous ydrochloric ac1d may beused as a catalyzer in the place of sul huric acid or the abovecatalyzers. When the above catalyzers are used instead of sulphuric acidthey are added to the reaction mixture until the evolution of gasceases.

Pentamethylene tetrazol is a white crystalline substance, melting pointis 57-58 (l,

readily soluble in water and in usual organic solvents. Solution reactsneutral.

Pentamethylene tetrazol crystallizes out of benzol in white crystals. Itis ve resistant to chemical action. Splitting with strong hydrochloricacid by heating to at least 250 C. and yields hydrogen, carbon dioxid,and pentamethylene diamine. It combines with one molecule of I-IgClwhich is dificultly soluble in water and melts at 175 C.

By the expressions carbonyl compounds I intend to include aldehydes,ketones or their derivatives which have a carbonyl group or compoundswhich during the reaction will give rise to compounds containing acarbonyl oup.

In p ace of acetone, cyclohexanone or benzophenone, pounds, for examplesuch as referred to in the above patent, namely, acetaldehyde andbenzaldehyde.

I claim 1. The process for the production of tetrazoles characterized inthat N H is caused to act, in excess, on carbonyl compounds 1n thepresence of concentrated mineral acid.

2. The process of producing tetrazoles comprising treating carbonylcompounds in the presence of concentrated mineral acid with an excess ofhydrazoic acid.

he process .of'producing tetrazoles comprising treating carbonylcompounds in the presence of concentrated mineral acid with an excess ofhydrazoic acid dissolved in a solvent thereof.

4. The process of producing tetrazoles comprising treating carbonylcompounds in the presence of concentrated mineral acid with an excess ofhydrazoic acid, the mixture being kept cool during the reaction period.

5. The process of producing tetrazoles comprising treating carbonylcompounds in the presence of concentrated mineral acid with an excess ofhydrazoic acid, and purifying the resulting tetrazol byrecrystallization.

'6. The process of treating organic compounds of the hydrocarbon type todirectly introduce therein amine nitrogen comprising I may use othercarbonyl com- Y adding thereto an excess of hydrazoic acid in thepresence of a catalyst.

7. The product pentamethylene tetrazol,

cn -cm-cn (in -cn --o i characterized by the following properties:crystallizes out of benzol in white crystals readily soluble in waterand most organic solvents with neutral chemical reaction; very resistantto chemical action, splits with strong hydrochloric acid upon heating toat least 250 C. and yields hydrogen, carbon dioxid andentamethylenediamin; and combines with one molecule I-IgCl which isdiificultly soluble in water and melts at 17 5.

8. The process of producing tetrazols comprising treating carbonylcompounds with an excess of hydrazoic acid in the presence of a catalystwhich will not the hydrazoic acid.

In testimony that I claim the foregoing as my invention, I have signedmy name hereto.

KARL FRIEDRICH SCHMIDT.

neutralize

